The present invention relates generally to gear reducers for use in modifying the output speed and torque of a prime mover such as an electric motor. In particular, the invention relates to a gearing commonality system for modular gear reducers designed to enable gear sets or gears from one stage, particularly from an input stage of a multi-stage gear reducer, to be used in other stages, particularly intermediate stages, of gear reducers in a family or series of products.
Gear reducers of various construction are known for converting output speeds and torques of prime movers to desired speeds and torques for an intended application, such as driving conveyors, rotating machinery and the like. Generally, such gear reducers include one or more intermeshing gear sets arranged on a series of shafts between an input and an output. The input is designed to be coupled to a prime mover such as an electric motor, while the output, typically a keyed shaft or sleeve, is coupled to the machine application to be driven. Multiple gear sets may be employed for further reduction of the speed beyond the limits of a single gear set.
In gear reducers of the type described above, it is generally known to provide several stages of reduction gearing arranged in a modular fashion. In this type of gear reducer, a base reduction gear set is typically housed in the main portion of the gear reducer, while an additional reduction gear set may be added by interfacing an additional housing element onto the base housing, thereby interfacing the additional gear set with the base gear set or sets. The overall gear reduction of the resulting multi-stage gear reducer is then the product of the ratios of the successive gear reduction sets. Typically, two reduction gear sets are provided in a base gear reducer to afford a range of gear reduction, and a third gear reduction set is adapted for mounting to the two-stage base reducer to provide a three-stage gear reducing system.
In conventional multi-stage gear reducers, it is generally known to provide a range of drive pinion sizes for each gear reduction stage, each pinion being designed to intermesh with a corresponding range of driven gears for those stages. Depending upon the gear reducer design, some limited commonality may be afforded by providing common parts between a second or input stage of a two-stage gear reducer and a third or input stage of a three-stage gear reducer. In general, such modularity is highly desirable in the design of a family of gear reducers because it permits a wide range of overall reduction ratios to be offered without greatly expanding the number of different gearing elements used to form the modules of the system. However, known multi-stage gear reducers generally do not employ the same gearing support structure for an intermediate stage of a three-stage gear reducer as they do for the input stages of either a two-stage gear reducer or three-stage gear reducer. In particular, while the input stage of a multi-stage gear reducer typically includes a shank-mounted or motor shaft-mounted pinion protruding into the first gear reduction stage and supported on one end only, intermediate stages of three-stage modular gear reducers typically include a shaft common to the driven gear of the first stage (which is typically bored for mounting on the common shaft) and to the pinion of the second stage supported on either end or at locations along the shaft by a pair of bearings. Consequently, in modular gear reducers of heretofore known design, no gearing commonality was generally afforded between input stages of either a two- or three-stage modular reducers and intermediate stages of such reducers.
There is a need, therefore, for an improved modular gear reducer system wherein greater commonality can be achieved between various stages of the gear reduction modules. Moreover, there is a particular need for multi-stage modular gear reducers wherein gearing commonality can be provided between input stages of two or three-stage gear reducers and intermediate stages of gear reducers having three or more stages. There is a further need for a system designed to provide, where possible, commonality between pinions and gearing of input stages of both two- and three-stage gear reducers and intermediate stages of three-stage reducers.